Orthodontics is a dental specialty that treats malocclusion through the movement of teeth as well as control and modification of facial growth. This process is usually accomplished by using a continuous mechanical force to induce bone remodeling, thereby enabling the teeth to move to a better position. In this approach, orthodontic appliances provide a continuous static force to the teeth via an archwire connected to brackets affixed to each tooth or via a removable appliance such as an aligner, or some similar accessory, that fits over the dentition. As the teeth slowly move due to the force, the force is dissipated. The archwires are adjusted to add additional force and to continue the desired tooth movement. Although effective, this widely accepted approach takes about twenty four months on average to achieve success.
Dental researchers have long postulated that a pulsating force might also be used to move teeth more rapidly and to ease the discomfort of traditional orthodontics.
For example, U.S. Pat. No. 4,244,688, U.S. Pat. No. 4,348,177, and U.S. Pat. No. 4,382,780 describe devices used to vibrate the teeth during orthodontic treatment, although each uses a different means of applying a vibration. The U.S. Pat. No. 4,244,688 employs a cumbersome external power source to power one to four small motors, whereas U.S. Pat. No. 4,348,177 uses pulsating fluids moved with the chewing motion of the jaw, and U.S. Pat. No. 4,382,780 uses a radio and speaker to set up a vibration. These devices are mounted on a bulky headgear that surrounds the head and are connected directly to the teeth by its intraoral portions. The devices are cumbersome, difficult to construct, expensive and are very difficult to use, thus reducing patient compliance.
U.S. Pat. No. 5,030,098 by Branford describes a hand-held device that simulates chewing in order to treat periodontal disease by increasing blood flow to the gums. The mouthpiece has a perforated malleable plate such that biting of the mouthpiece results in the plate adapting to the user's bite which, of course, varies with each user. The external vibrator imparts motion to the mouthpiece and thus the user's teeth. The device, however, uses an external power source. Further, the dental plate is brass, and is very unpleasant to bite on, thus necessitating a second exterior coating and further complicating manufacture and cost. Although this device allows some small degree of masticating movement by the user, the degree of motion is actually very small. Further, since the device is not designed for orthodontic use, there is no motivation to modify the device to allow a greater degree of movement.
U.S. Pat. No. 5,967,784 by Powers describes a similar device to that described by Brandford. It too is a hand-held tooth vibrator that is simple and has an exterior motor housing connected to a vibrating interdental mouthpiece portion for gripping between the teeth of the patient. The exterior housing contains a battery and a switch for selectively operating a motor with an off-center weight attached to the motor rotating shaft for creating a high frequency vibration that vibrates the entire device. The mouthpiece is disposable, making the system affordable and more convenient to use. The patent teaches using the device to alleviate pain by inserting the interdental mouthpiece between the teeth and clenching and releasing the teeth over the mouthpiece, in an attempt to engage as many teeth as possible in the transmitted vibrations. The vibration is believed to alleviate discomfort by increasing blood flow.
The devices of Branford and Powers are superficially similar to those of the invention herein, but there are significant differences. Most importantly, there is no recognition in either patent that the vibratory device can be used for alveolar bone remodeling or more rapid tooth movement. Thus, the shape of the dental plate in each case is a very flat U- or Y-shaped member that is largely ineffective for remodeling dentoalveolar bone. Additionally, the vibration is not optimized in frequency and amplitude for remodeling. Finally, neither device is programmable, nor can teeth be differentially vibrated, thus the dentist cannot optimize its usage for each patient, nor monitor patient compliance. All of these shortcomings reduce the effectiveness of these devices for craniofacial bone tissue remodeling uses.
U.S. Pat. No. 6,632,088 describes a bracket with powered actuator mounted thereto to provide vibration, but this device appears to be held completely internal to the patient's mouth, thus again being cumbersome, and thus may affect patient comfort and ultimately patient acceptance of the device.
Mao was probably the first to show that the use of cyclic forces could improve dental straightening in rabbits (see U.S. Pat. No. 6,684,639, U.S. Pat. No. 6,832,912, U.S. Pat. No. 7,029,276). Certain dynamic loading patterns (cycling force with rest periods) were shown to greatly increase bone formation compared to basic dynamic loading. Inserting rest periods is now known to be especially efficacious as it allows mechanosensitivity to be restored to the bone tissue. A point of diminishing returns is reached within each loading session. Therefore, intermittently loading cyclic force can increase the rate of bone formation significantly.
However, the device provided by Mao for use in laboratory animals uses arch wires and brackets with a centrally mounted motor that is held inside the mouth. Therefore, the device would be uncomfortable for the patient to use and there is always some risk of electric shock.
Kajimoto, U.S. Pat. No. 7,163,399, describes a device capable of differential vibration. It is an ultrasonic therapy device with an oscillator embedded in the body and holding members which hold the body next to the affected area. The bodies are fixed in the oral cavity next to an implant to accelerate osteogenesis around implant fixtures by supplying an ultrasonic signal from an external driver to the oscillator. This device is only used with an implant, and does not appear suitable for general orthodontic use.
Mailyan, U.S. Pat. No. 7,192,281, also describes a vibrational system for encouraging osteogenesis. Mailyan inserts plates at growth zones for palatal and jaw defect repair. The plates are vibrated to stimulate neogenesis of bone tissue, and then resized to allow further growth. The process uses the mechanical forces of the jaw to apply pressure to missing palatal bone or a honey jaw defect.
JP2007260158 describes a device capable of differential vibration by virtue of holes in the bite plate. Thus, no vibration is transmitted to those teeth in the holes. Each device however, must be custom made for the patient in order to have the correct fit and hole placement and would require continuous revisions to work in orthodontic treatments.
US20080227047 and US20080227046 by Applicants presents a device that accelerates bone remodeling via non-static loading and includes an extraoral vibratory source and a removable and replaceable intraoral bite plate. However, this device can be further optimized and improved by accessories and/or improved design, materials and engineering, and the inventions described herein provide those improvements.